Melatonin in adult insomnia

Melatonin is the primary regulatory hormone of the circadian rhythm in humans

• is secreted by the pineal gland and synthesized from serotonin, which originates from tryptophan, a natural mild sedative
• peaks in low light and is suppressed by daylight
• the onset of its secretion positively correlates with sleepiness
• peak nocturnal melatonin concentrations decline with age, and delayed peaks are associated with sleep disorders in older adults (1)
• due to its role in regulating the circadian rhythm, melatonin has been used to prevent delirium in older hospitalized patients (1)
• a controlled-release formulation of melatonin (Circadin® 2 mg) was first approved by the European Medicines Agency (EMA) as a monotherapy for the short-term treatment of primary insomnia in elderly patients aged over 55 years (2)
• in the UK melatonin is licensed for short-term use in the management of insomnia (3):
  • for adults 55 years and over
    • 2 mg once daily for up to 13 weeks, dose to be taken 1-2 hours before bedtime
  • Jet lag [short-term use] for melatonin
    • by mouth using immediate-release medicines
    • Adult
      • 3 mg once daily for up to 5 days, the first dose should be taken at the habitual bedtime after arrival at destination
      • doses should not be taken before 8 p.m. or after 4 a.m, dose may be increased to 5 or 6 mg once daily if necessary, or reduced to 1 or 2 mg once daily if sufficient
      • maximum of 16 treatment courses per year

Check the respective Summary of Product Characteristics (SPC) before prescribing melatonin.

Notes:

• Circadin® is licensed for the short-term treatment of primary insomnia in adults aged 55 years and over, and some immediate-release formulations, such as Adaflex®, Ceyesto®, and Syncrodin®, are licensed for the short-term treatment of jet lag in adults

Reference:

1. Salahub C, Wu PE, Burry LD, Soong C, Sheehan KA, MacMillan TE, Lapointe-Shaw L. Melatonin for Insomnia in Medical Inpatients: A Narrative Review. J Clin Med. 2022 Dec 29;12(1):256.
2. Kim HK, Yang KI. Melatonin and melatonergic drugs in sleep disorders. Transl Clin Pharmacol. 2022 Dec;30(4):163-171
3. NICE - British National Formulary (BNF). Melatonin (accessed 8/5/2024)